THE *' PRO-EMBKYO" OF CHARA. 355 



remarkable plant will bear the name of my colleague, A.' G. 

 More, Esq., who first called attention to it, and who has con- 

 tributed in so many instances to the furtherance of British botany. 



Desceiption of Tab. 199. — Isoetes Morei, D. Moore, from specimens 

 collected at Lough Bray, Ireland. 1. A complete plant. 2. Vertical section of 

 the corra. 3. Transverse section of the same. 4, Lower portion of a leaf, 

 showing macrosporangium, veil and lingula. 5. Transverse section of micro- 

 sporangium. 6. Transverse section of leaf. 7. Macrospores. 



[N.B. — In section No. 4 the lingula is shewn too narrow at hase, with 

 margins more entire than they usually are.] 



THE ''PKO-EMBKYO" OF CHARA: AN ESSAY IN 



MORPHOLOGY. 



By Sydney H. Vines, B.A., B.Sc, F.L.S., Fellow and Lecturer 



of Christ's College, Cambridge. 



It is to the researches of Pringsheim"^ that we are indebted for 

 our knowledge of the fact that the fertilised oosphere of Chara does 

 not immediately give rise, as had been stated by previous observers, 

 to the sexual plant, but that a comparatively inconspicuous 

 "pro-embryo" (Vorkeim) is developed from it, which presents no 

 differentiation of stem and leaf, from one of the cells of which the 

 axis of the sexual differentiated j)lant is formed as a lateral out- 

 growth. The details of the development of the " pro-embryo " 

 have been recently described by De Bary.f From his description 

 and figures it appears that the first stage in its development con- 

 sists in the disappearance of the granules of starch and fatty 

 matter from the protoplasm occupying the apex (free end) of the 

 cell, and in the formation of a wall at right angles to its long axis 

 as to divide it into two unequal cells — a small apical cell filled with 

 hyaline protojDlasm, and a much larger basal cell, the protoplasm 

 of which is full of granules. The basal cell appears to act merely 

 as a depository for nutrient materials to be used in the growth of 

 the " pro-embryo," which is formed from the small apical cell in 

 the following manner : — It is divided into two equal parts by the 

 formation of a wall perpendicular to the first, lying therefore in 

 the plane of the long axis of the oospore, t Each of the two cells 

 thus formed grows out into a multicellular filament, the one being 

 the " ]3ro- embryo," the other the " primary root." 



It is not necessary to follow the succession of cell-divisions 

 whichlead to the formation of these structm-es, nor is it essential to 

 reproduce here Pringsheim's account of the development of the 

 axis of the sexual plant from one of the cells of the " ^Dro-embryo." 

 What has been said above will be found sufficient to render intel- 

 ligible the following discussion, which has for its object the 

 elucidation of the morphological significance of the " pro-embryo." 



* ' Jahrb. fiir wiss. Bot.' Bd. iii. 1864, p. 294. 



+ • Bot. Zeitg.' 1875, p. 877 (trans, in Journ. Bot., 1875, p. 298) ; also « Nordstedt, 

 and Wahlstedt, Flora,' 1875. 



+ Oospore = fertilised oosphere (central cell, gynosphere, ovum). 



